Atherosclerosis and cancer are the two major causes of morbidity and mortality in western societies. While there has been significant advance in the treatment of atherosclerosis there is still a great need for more effective treatment interventions.
The main mechanism by which atherosclerosis leads to morbidity and mortality is by narrowing the lumen of arteries and reducing the blood supply to the heart, brain and other vital organs. The factors associated with atherosclerosis include: High levels of cholesterol, triglycerides, low density lipoproteins (LDL) and low levels of high density lipoproteins (HDL).
Other factors are heredity, cigarette smoking, obesity, high blood pressure, reduced physical activity, high fat diets, and a high oxidation activity associated with the production of free radicals, leading to the oxidation of LDL, which accelerates the development of atherosclerotic lesions. Thus, J. Regnstrxc3x6m et al., Lancet, Vol. 339, No. 8803, May 16, 1992, pp. 1183-86, reported that the susceptibility of LDL to in vitro oxidation in the presence of copper, which acts as a catalyst in the oxidation process, was correlated with the severity of their coronary artery sclerosis. J. T. Salonen et al, Lancet, Vol. 339, No. 8798, Apr. 11, 1992, pp. 883-87, found that the level of autoantibodies to oxidized LDL predicted the progression of atherosclerosis of the carotid artery (the artery that supplies blood to the brain). One likely mechanism in development of atherosclerotic lesions via the oxidation of LDL is the induction of an autoimmune process leading to the production of antibodies specific to oxidized LDL and propagation of the atherosclerotic lesion by the autoantibody binding to oxidized LDL. J. Regnstrxc3x6m et al., supra, and T. Kita et al., Proceedings of the National Academy of Sciences USA, Vol. 84, 1987, pp. 5928-31. J. T. Salonen et al., Circulation, Vol. 86(3), September 1992, pp. 803-11 reported an association between the risk of heart attack and the level of iron in the blood, with the risk being particularly high when plasma levels of both iron and LDL were elevated.
A significant reduction in blood levels of LDL and cholesterol by diet and lipid reducing drugs was found to result in regression of atherosclerosis. G. Brown et al., New England Journal of Medicine, Vol. 323(19), Nov. 8, 1990, pp. 1289-1298. Oral lipid lowering drugs, such as Lovastatin, MSD (MEVACOR(copyright), Merck), are risky and may cause liver damage. Their efficacy is relatively limited, even when they are taken in association with a strict diet. Lowering of LDL by extracorporeal treatment of blood, M. Strahilevitz, U.S. Pat. Nos. 4,375,414 and 4,813,924, and M. Strahilevitz, Atherosclerosis, Vol. 26, 1977, pp. 373-77, is significantly more effective in reducing blood cholesterol and LDL levels. H. Borberg et al., Journal of Clinical Apheresis, Vol. 4, 1988, pp. 59-65; R. L. Wingard et al., American Journal of Kidney Diseases, Vol. 18(5), 1991, pp. 559-65; V. Hombach et al., Dtsch Med. Wschr, Vol. 111(45), 1986, pp. 1709-15. LDL and cholesterol can be removed by affinity adsorption, utilizing as the adsorbent antibodies to LDL or other specific chemical adsorbents, such as dextran sulphate (M. Odaka et al., International Journal of Artificial Organs, Vol. 9, 1986, pp. 343-48) or heparin (D. J. Lupien et al., Pediatric Res., Vol. 14, 1980, pp. 113-17). LDL removal can also be achieved by heparin precipitation (D. Seidel et al., Journal of Clinical Apheresis, Vol. 4, 1988, pp. 78-81), and by double filtration plasmapheresis (S. Yokoyama et al., Arteriosclerosis, Vol. 5, November/December 1985, pp. 613-22) as well as by plasma exchange (G. R. Thompson, Lancet, 1981 I, pp. 1246-48).
The oral administration of vitamin E is associated with lower risk of coronary heart disease in men (E. B. Rimm et al., New England Journal of Medicine, Vol. 328(20), May 20, 1993, pp. 1450-56) and in middle aged women (M. J. Stampfer et al., New England Journal of Medicine, Vol. 328(20), May 20, 1993, pp. 1487-89). The mechanism of this protective effect is based on the antioxidant property of vitamin E, which inhibits the oxidation of LDL, thus exerting a protective effect from the development of atherosclerosis. The oxidation of LDL is catalyzed by heavy metals such as iron and copper. The removal of the metals by intravenous administration of chelating agents was reported to be effective in atherosclerotic vascular disease. E. Olszewer and J. P. Carter, Medical Hypotheses, Vol. 27(1), September 1988, pp. 41-49, and E. Cranton, xe2x80x9cBypassing Bypass,xe2x80x9d Hampton Road Publishers, Norfolk, V.a, 1992. Others did not confirm these reports. S. R. Wirebaugh and D. R. Gerates, DICP, Vol. 24(1), January 1990, pp. 22-24.
The apparent minimal effect, or lack of effect, of intravenous chelation in the treatment of atherosclerosis can be overcome by extracorporeal chelation which significantly increases chelation efficacy and reduces significantly its toxicity. M. Strahilevitz, Lancet. Vol. 340, Jul. 25, 1992, p. 235.
Extracorporeal chelation with desferoxamine was highly effective and safe in reducing blood iron in the treatment of hemochromatosis, a disease caused by the accumulation of excess iron in the blood and body stores. J. L. Held et al., Journal of American Academy of Dermatologists, Vol. 28, 1993, pp. 253-54. Ambrus and Horvath in U.S. Pat. No. 4,612,122 also describe a specific column configuration that can be used for extracorporeal chelation. In this column the chelating agent is physically immobilized in the spongy outer part of an anisotropic (asymmetrical) membrane.
Chelating agents can also be utilized with the extracorporeal affinity adsorption devices of Strahilevitz, U.S. Pat. No. 4,375,414.
Coronary bypass surgery is effective in reducing symptomatology, but its effect on mortality is limited. J. H. O""Keefe, Jr. and B. D. McCallister, Editorial, Mayo Clinic Proceedings, Vol. 67, 1992, pp. 389-91, R. D. Simari et al., Mayo Clinic Proceedings, Vol. 67, April 1992, pp. 317-22.
Bypass surgery has no curative effect on the atherosclerotic disease process. The problem of post surgery atherosclerosis progression and the development of coronary or graft restenosis are major problems associated with bypass surgery. The need for effective means for reducing progression and inducing regression of atherosclerosis in patients following bypass surgery is well recognized, as is the need to further develop effective nonsurgical treatments that would replace bypass surgery in a significant proportion of patients that are currently being treated with bypass surgery, because of the lack of alternative effective medical treatment.
This is particularly relevant for candidates for bypass coronary surgery with moderately severe coronary occlusion that may not exhibit significant fibrotic changes in the atherosclerotic coronary lesions. Similar limitations to those of bypass surgery apply to percutaneous transluminal coronary angioplasty. Simari et al., supra. In this procedure, an inflatable balloon is inserted into the coronary occlusion site. As with bypass surgery, this procedure also has no effect on the atherosclerotic disease process, thus restenosis is a significant problem. While the risks associated with angioplasty are lower than with bypass surgery, this is also an invasive procedure associated with morbidity and mortality risks.
While current medical treatments, particularly when combinations of conventional treatments are utilized, have significant effect in reducing progression and in inducing regression of the atherosclerotic process (Brown et al., supra), there is a need to have more effective treatment methods, particularly for those who can not be treated with oral lipid lowering drugs because of liver toxicity, who are unable to maintain a strict diet, or who fail to improve with conventional treatment, including oral lipid lowering drugs and diet.
The utilization of extracorporeal affinity adsorption of LDL (Strahilevitz, supra) can lead to marked reduction in LDL level, thus to significant regression of atherosclerotic coronary lesions. Hombach et al., supra. However, the effect of affinity adsorption of LDL and cholesterol, while aimed at a major factor in atherosclerosis, hyperlipidemia, is selectively targeted on this factor. Even when (as usually is the case) the affinity LDL adsorption is utilized with other measures (diet, exercise etc.) the quantitative impact of these conventional treatment methods may not be sufficient. The availability of non-surgical methods that will have a significantly larger quantitative effect on additional factors that are involved in the etiology and pathogenesis of atherosclerosis is of great importance, in order to optimize the non-surgical and post-surgical treatment of atherosclerosis.
One of the objects of the present invention is to provide effective non-surgical treatments of atherosclerosis.
Another object is to provide improvements in extracorporeal treatment methods for atherosclerosis and other diseases.
Another object is to provide improved specific affinity devices, particularly immunoadsorption devices, and methods.
Other objects will become apparent to those skilled in the art in light of the following description.
In accordance with one aspect of the present invention, methods and devices for treating atherosclerosis and other conditions are provided that are based on the utilization of specific affinity adsorption of several of the biological molecules that are etiological in the pathogenesis of the condition. The affinity adsorbents utilized in accordance with the present invention are both immunoadsorbents and non-immune-based specific affinity chemical adsorbents.
In some applications of extracorporeal combined treatment, one or both of the extracorporeal methods may be based on other principles than adsorption, for example use of extracorporeal double filtration for the removal of LDL. S. Yokoyama et al., supra.
The adsorbents are incorporated in an extracorporeal treatment device. The methods of the present invention will be usually utilized in conjunction with conventional treatment methods, both medical and, when indicated, surgical methods.
The novel treatment methods that are the subject of the present invention are based on and are specific improvements of extracorporeal affinity adsorption and extracorporeal affinity dialysis which are disclosed in Strahilevitz U.S. Pat. Nos. 4,375,414 and 4,813,924 and British provisional patent application No. 16001, May 20, 1971, and which are incorporated herein by reference.
It is one of the objects of the present invention to provide additional specific improvements and embodiments to further increase the effectiveness and utility of extracorporeal affinity adsorption treatment of atherosclerosis.
Many of the elements of the present invention, as it applies to the treatment of atherosclerosis, are discussed in M. Strahilevitz, Lancet, Vol. 340, Jul. 25, 1992, p. 235, which is incorporated herein by reference.
One aspect of the present invention is to provide novel extracorporeal treatments for atherosclerosis based on specific affinity adsorption. The present invention also improves the efficacy of extracorporeal LDL affinity adsorption by combining it with affinity adsorption of ligands other than LDL and other lipids, that are also etiological in atherosclerosis.
Another aspect of the present invention is providing means for reducing the level of oxidized LDL in the body, using as affinity adsorbents specific antibodies to oxidized LDL, or using as specific adsorbent enzymatic digestion fragments of such antibodies, or synthetic fragments of such antibodies.
Yet another aspect of the invention is improving the immunoaffinity adsorption of LDL through the utilization of specific synthetic fragments of antibody (G. W. Welling et al., Journal of Chromatography, Vol. 512, 1990, pp. 337-43), with synthetic fragments that are specific to LDL. Yet another aspect is providing means for extracorporeal affinity adsorption of autoantibodies to oxidized LDL, which may be etiological in atherosclerosis, by using as the specific adsorbent oxidized LDL (the antigen) such as malondialdehyde LDL (Salonen, Lancet, supra), or to use as the adsorbent of oxidized LDL autoantibodies, Staphylococcal Protein A (Strahilevitz, Lancet, supra). Rather than Staphylococcal Protein A, a recombinant Staphylococcal Protein A or Staphylococcal Protein A component, or other synthetic peptides of Staphylococcal Protein A may be utilized, as may Protein G or its components. Bensinger, U.S. Pat. No. 4,614,513; R. Lindmark et al., J. Immunological Methods, Vol. 62, 1983, p. 1. As used herein, except when the context clearly indicates otherwise, the terms xe2x80x9cProtein Axe2x80x9d and xe2x80x9cProtein Gxe2x80x9d include all such variations.
When fragments of antibodies are used in the present invention as affinity adsorbents, they can be produced by enzymatic (e.g., papain or pepsin) digestion of the intact antibody to produce Fab, (Fabxe2x80x2)2, or FV antigen-binding fragments, or they can be produced by other methods known to those skilled in the art for the synthesis of peptides, such as solid phase synthesis (R. A. Houghten, Proc. National Academy of Science USA, Vol. 82, August 1985, pp. 5131-35; R. E. Bird et al., Science, Vol. 242, 1988, pp. 423-42) or through genetic engineering in a suitable vector such as E. Coli or phage (J. W. Larrick, Pharmacological Reviews, Vol. 41(4), 1989, pp. 539-57). The use of fragments, rather than intact antibodies, as the affinity adsorbent may increase the adsorption capacity and reduces side effects that may be associated with the Fc non-antigen binding part of the antibody molecule.
Another objective of the invention is to provide for extracorporeal chelation therapy for cancer, autoimmune diseases and degenerative diseases, such as rheumatoid arthritis.
An additional objective is to provide extracorporeal combined treatment of cancer based on combining extracorporeal chelation and extracorporeal adsorption of enhancing tumor antibodies and their complexes by utilizing one or more of the following specific adsorbents, (a) Tumor specific antigen and (b) Staphylococcal Protein A or Protein G.